IRX 4-6 are therapeutic cancer vaccine candidates that combine IRX-2 and defined tumor antigens. The Company believes that by combining cancer antigens with IRX-2, targeted vaccines can be formulated that may further unlock the cellular response and build on the encouraging results of IRX-2.

IRX-4 is the combination of IRX-2 and prostate specific membrane antigen (PSMA) peptides and is targeted at patients with prostate cancer. Pre-clinical work has demonstrated a vibrant PSMA-peptide specific immune response in mice treated with IRX-4.

The Company intends to open an IND for IRX-4 as a therapy for late-stage or recurrent prostate cancer.

Other potential indications for therapeutic cancer vaccines include lung cancer, breast cancer, and melanoma.